Huan Tan1,
  Ioannis Koktzoglou2, 3, Pottumarthi Vara Prasad2,
  3
 1NorthShore
  University HealthSystem, Evanston , IL, United States; 2NorthShore
  University HealthSystem, Evanston, IL, United States; 3The
  University of Chicago Pritzker School of Medicine, Chicago, IL, United States
A single breath-hold scan does not provide enough time for signal averaging needed by arterial spin labeling technique in renal perfusion measurement. In our study, we have implemented a novel two-dimensional (2D) navigator technique in concert with FAIR True-FISP to minimize respiratory motion via retrospective reconstruction and allow for multiple averages during free-breathing acquisition. The 2D navigator-gated approach achieved good image quality in patients while the breath-hold results were unusable. Given the limitation of using contrast agents in patients with compromised renal function, free breathing ASL offers a non-invasive method to evaluate renal perfusion.